|
Linnett Double-Quartet Theory
Linnett double-quartet theory (LDQ) is a method of describing the Covalent bond, bonding in molecules which involves separating the electrons depending on their Electron spin, spin, placing them into separate 'spin tetrahedra' to minimise the Pauli repulsions between electrons of the same spin. Introduced by J. W. Linnett in his 1961 monograph and 1964 book, this method expands on the Lewis structure, electron dot structures pioneered by Gilbert N. Lewis, G. N. Lewis. While the theory retains the requirement for fulfilling the octet rule, it dispenses with the need to force electrons into Electron pair, coincident pairs. Instead, the theory stipulates that the four electrons of a given spin should Coulombic force, maximise the distances between each other, resulting in a net tetrahedral electronic arrangement that is the fundamental molecular building block of the theory. By taking cognisance of both the Electric charge, charge and the spin of the electrons, the theory can describe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
O3 2D Structure
O3 may refer to: *O3, the molecular formula for ozone *''O3'', the 1993 debut album by the techno band Sunscreem *''O3 A Trilogy'', a 2008 concept album trilogy by progressive metal band Dominici *O3 star, in stellar classification, a subclass of type O stars * O-3, the pay grade for the following officer ranks in the U.S. uniformed services: ** Captain in the Army, Marine Corps, Air Force, and Space Force ** Lieutenant in the Navy, Coast Guard, Public Health Service Commissioned Corps, and NOAA Commissioned Officer Corps *O3 Entertainment, a video game publisher *Haplogroup O3 (Y-DNA), a Y-DNA Haplogroup *Oldershaw O-3, glider * USS ''O-3'' (SS-64), a 1917 United States O class submarine * Otoyol 3, a Turkish motorway from Edirne to Istanbul *Oskarshamn 3, unit 3 at Oskarshamn Nuclear Power Plant in Sweden * ''O3'' (album), a 2008 album by Son of Dave See also * 03 (other) * Ö3, Austrian radio station * 3O (other) 3O or 3-O may refer to: *3J, IATA code f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radical (chemistry)
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉) which have two unpaired electrons. Radicals may be generated in a number of ways, but typical methods involve redox reactions. Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations. Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formal Charge
In chemistry, a formal charge (F.C. or q), in the covalent view of chemical bonding, is the charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity. In simple terms, formal charge is the difference between the number of valence electrons of an atom in a neutral free state and the number assigned to that atom in a Lewis structure. When determining the best Lewis structure (or predominant resonance structure) for a molecule, the structure is chosen such that the formal charge on each of the atoms is as close to zero as possible. The formal charge of any atom in a molecule can be calculated by the following equation: F = V - L - \frac where ''F'' is the formal charge; ''V'' is the number of valence electrons of the neutral atom in isolation (in its ground state); ''L'' is the number of non-bonding valence electrons on this atom in the molecule; and ''B'' is the total number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jack Linnett
John Wilfrid Linnett FRS (3 August 1913 – 7 November 1975) was Vice-Chancellor at the University of Cambridge from 1973 to 1975. He was for many years a Fellow of the Queen's College, Oxford, and a demonstrator in Inorganic Chemistry at the University of Oxford. Education He was born on 3 August 1913 in Coventry in England and educated at King Henry VIII School and St John's College, University of Oxford, and was later a Junior Fellow there. Academic career He was appointed Professor of Physical Chemistry at Cambridge University in 1965. He was Master of Sidney Sussex College, Cambridge, on the Council of the Royal Society, and was President of the Faraday Society. Throughout his career as a chemist, he was noted for his wide interests, making substantial contributions in theoretical chemistry, mass spectrometry, explosion limits, atom recombination reactions, combustion, and several other areas. Octet rule In 1960, Linnett originated a modification to the octet rule, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Lennard-Jones
Sir John Edward Lennard-Jones (27 October 1894 – 1 November 1954) was a British mathematician and professor of theoretical physics at the University of Bristol, and then of theoretical science at the University of Cambridge. He was an important pioneer in the development of modern computational chemistry and theoretical chemistry. Early life and education Lennard-Jones was born on 27 October 1894 at Leigh, Lancashire, the eldest son of Mary Ellen and Hugh Jones, an insurance agent. He was educated at Leigh Grammar School, going on to study at the University of Manchester, graduating in 1915 with a first-class honours degree in mathematics. Career Lennard-Jones is well known among scientists for his work on molecular structure, valency and intermolecular forces. Much research of these topics over several decades grew from a paper he published in 1929. His theories of liquids and of surface catalysis also remain influential. He wrote few, albeit influential, papers. His ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pauli Exclusion Principle
In quantum mechanics, the Pauli exclusion principle states that two or more identical particles with half-integer spins (i.e. fermions) cannot occupy the same quantum state within a quantum system simultaneously. This principle was formulated by Austrian physicist Wolfgang Pauli in 1925 for electrons, and later extended to all fermions with his spin–statistics theorem of 1940. In the case of electrons in atoms, it can be stated as follows: it is impossible for two electrons of a poly-electron atom to have the same values of the four quantum numbers: ''n'', the principal quantum number; ', the azimuthal quantum number; ''m'', the magnetic quantum number; and ''ms'', the spin quantum number. For example, if two electrons reside in the same orbital, then their ''n'', ', and ''m'' values are the same; therefore their ''ms'' must be different, and thus the electrons must have opposite half-integer spin projections of 1/2 and −1/2. Particles with an integer spin, or bosons, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stern–Gerlach Experiment
The Stern–Gerlach experiment demonstrated that the spatial orientation of angular momentum is quantized. Thus an atomic-scale system was shown to have intrinsically quantum properties. In the original experiment, silver atoms were sent through a spatially varying magnetic field, which deflected them before they struck a detector screen, such as a glass slide. Particles with non-zero magnetic moment are deflected, due to the magnetic field gradient, from a straight path. The screen reveals discrete points of accumulation, rather than a continuous distribution, owing to their quantized spin. Historically, this experiment was decisive in convincing physicists of the reality of angular-momentum quantization in all atomic-scale systems. After its conception by Otto Stern in 1921, the experiment was first successfully conducted by Walther Gerlach in early 1922. Description The Stern–Gerlach experiment involves sending a beam of silver atoms through an inhomogeneous magnetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Magnetic Moment
In atomic physics, the electron magnetic moment, or more specifically the electron magnetic dipole moment, is the magnetic moment of an electron resulting from its intrinsic properties of spin (physics), spin and electric charge. The value of the electron magnetic moment is The electron magnetic moment has been measured to an accuracy of relative to the Bohr magneton. Magnetic moment of an electron The electron is a charged particle with charge −, where is the elementary charge, unit of elementary charge. Its angular momentum comes from two types of rotation: Spin (physics), spin and orbital motion. From classical electrodynamics, a rotating distribution of electric charge produces a magnetic dipole, so that it behaves like a tiny bar magnet. One consequence is that an external magnetic field exerts a Magnetic moment#Torque on a moment, torque on the electron magnetic moment that depends on the orientation of this dipole with respect to the field. If the electron is visuali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Nucleus
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by Dmitri Ivanenko and Werner Heisenberg. An atom is composed of a positively charged nucleus, with a cloud of negatively charged electrons surrounding it, bound together by electrostatic force. Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. Protons and neutrons are bound together to form a nucleus by the nuclear force. The diameter of the nucleus is in the range of () for hydrogen (the diameter of a single proton) to about for uranium. These dimensions are much smaller than the diameter of the atom itself (nucleus + electron cloud), by a factor of about 26,634 (uranium atomic radiu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Pair
In chemistry, an electron pair or Lewis pair consists of two electrons that occupy the same molecular orbital but have opposite spins. Gilbert N. Lewis introduced the concepts of both the electron pair and the covalent bond in a landmark paper he published in 1916. Because electrons are fermions, the Pauli exclusion principle forbids these particles from having the same quantum numbers. Therefore, for two electrons to occupy the same orbital, and thereby have the same orbital quantum number, they must have different spin quantum number. This also limits the number of electrons in the same orbital to two. The pairing of spins is often energetically favorable, and electron pairs therefore play a large role in chemistry. They can form a chemical bond between two atoms, or they can occur as a lone pair of valence electrons. They also fill the core levels of an atom. Because the spins are paired, the magnetic moment of the electrons cancel one another, and the pair's contri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Bond
A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules and crystals. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding. Strong chemical bonding arises from the sharing or transfer of electrons between the participating atoms. Since opposite electric charges attract, the negatively charged electrons surrounding the nucleus and the positively charged protons within a nucleus attract each other. An electron positioned between two nuclei will be attracted to both of them, and the nuclei will be attracted toward electrons in this position. This attraction constitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-center Bond , found in hypervalent compounds such as the noble gas compounds
{{chemistry index ...
In chemistry, there are two types of three-center bonds: *Three-center two-electron bond, found in electron-deficient compounds such as boranes *Three-center four-electron bond The 3-center 4-electron (3c–4e) bond is a model used to explain bonding in certain hypervalent molecules such as tetratomic and hexatomic interhalogen compounds, sulfur tetrafluoride, the xenon fluorides, and the bifluoride ion. It is also know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
